It's not a question of hierarchy: you're just saying you want no hyphenation, nada, rien, nicht. Indeed, with \usepackage[none]{hyphenat} you disable all hyphenation, so, no matter what and how many hyphenation exceptions you define, they won't be used.
Why would anybody want no hyphenation throughout a document is beyond my understanding. Hyphenation is good, provided it's not too frequent; it is used in books of the finest quality and there can be no serious objection to it. If the text width is set carefully, a language like English needs very few hyphens; of course, in narrow columns it will become more frequent.
The only way to avoid hyphenation in a consistent way is to set the text raggedright: justification would be out of the question. There are too many word processed document around that show the ugliness of justified text without hyphenation: please don't contribute to pollution. ;-)
hyperrefpackage, which generally should be loaded last (with some specific exceptions). See Which packages should be loaded after hyperref instead of before? – Alan Munn Jan 20 '14 at 19:56